An Light-Emitting Diode (LED) is a semiconductor light source, which have many practical applications due to their longer lifetime, faster switching, smaller physical size, greater durability and higher energy efficiency.
When a light-emitting diode is forward biased, electrons (negative charges) recombine with holes (positive charges), which releases energy in the form of photons. The energy difference within the diode produces photons of different wavelengths, for different colors, which do not require color filters to produce. LEDs are solid state devices and if operated at low currents and at low temperatures, are subject to very limited wear and tear. Typical lifetimes are estimated to be 35,000 to 50,000 hours of useful life, compared to 10,000 to 15,000 hours for fluorescent tubes, and 1,000-2,000 hours for incandescent light bulbs. LEDs are also less fragile than fluorescent and incandescent bulbs, and are less susceptible to damage by external vibration.
LEDs produce more light per watt than incandescent bulbs, and are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently. LEDs can very easily be dimmed continuously unlike fluorescent lamps which require a certain threshold voltage to maintain illumination.
LEDs have been found to have significant environmental benefits compared to other alternatives. It has been estimated that a building's carbon footprint from lighting can be reduced by 68% by exchanging all incandescent bulbs for new LEDs. LEDs are also non-toxic compared to compact fluorescent, which contains traces of mercury. Organic light emitting diodes (OLEDs) can be produced that use an organic compound as the emitting layer material of the LED, which can be a polymer.
Performance of LEDs is temperature dependent, and LED light output actually increases at cold temperatures. LEDs do not generate as much heat as incandescent bulbs, by not producing invisible light in the infrared range, but they do produce internal heat which must be dissipated if the LED is to maintain good performance. Over-heating of the LED is a major factor in device failure. Heat sinks are necessary to maintain long life of the LED. This is especially important to have a low failure rate when LEDs are used in automotive, medical, and military applications where the device must operate over a large range of temperatures, and failure could create serious problems.
Heat sinks are currently available for LEDs, but any improvement in cooling can increase device operations and reliability. Some heat sinks are made very simply. They incorporate different numbers of cooling fins. Some have a little and some have many. The thinking for some developers is to add more fins and deeper fins. This does provide some cooling effect for the heat sink, as just using fins of any kind helps somewhat. However, the right balance of parameters is important in providing improved cooling. For example, if the fins are too deep, it works in reverse, and heat is maintained. Therefore, it is important to consider many parameters and their interaction to provide improved heat transfer, and more efficient cooling, and therefore better performance and longer lifespan of the LEDs.
Thus, there is need for an LED heat sink cooling system that has improved cooling properties, and thus produces improved device performance for LEDs.